MINERAL WOOL PRODUCT, METHOD FOR ITS PRODUCTION, IMPREGNATING MASS THEREFOR, AND USE THEREOF

Abstract: The surfaces of coated mineral fiber products, as a rule, also form a barrier against dust and trickling particles, are however not accepted for technological reasons and reasons of cost unless their intended use requires coating or impregnating for different reasons. In order to provide such mineral wool products, which - in view of their use - usually are not coated, with a barrier against dust or trickling particles, it is proposed to provide their surfaces with an impregnating mass applied in a foamed form. The froth is destroyed during drying or curing to open macroscopic pores between the fibers, whereby an open surface structure of the product is preserved. Nevertheless the impregnated layer offers effective protection against solid matter passing through it. Impregnation by means of a foam incurs surprisingly low additional costs, even in large series production. It is of particular importance that by selecting a suitable impregnating mass, the tactile sensation of the product may be modified in a desired manner such that the product will e.g. be softer or warmer to the touch.

Description: Description Mineral Wool Product, Method For Its Production, Impregnating Mass Herefor, and Use Thereof The invention concerns a mineral wool product com¬ prising an impregnating layer on at least one surface thereof, which is located substantially in the region within the mineral wool adjacent the product surface. It furthermore concerns a particulary suitable method for its production and a further use of the impregnating mass. Mineral wool products comprising a coating or impreg¬ nating layer at the surface essentially within the region adjacent the product surface are e.g. known from EP 0 114 965 Bl. In the known case, these are insulating panels for the front surfaces of supporting structures or for roofs, which require a coating or impregnating layer in order to be able to serve as plaster-bearing panels or to prevent the penetration of bitumen into the panel. This simultaneously results in a strengthening of the coated or impregnated surface and in a certain effect of sealing the surface due to the coating or impregnating layer. Coating or impregnating layers intended for specific purposes present properties which are adapted to these respective purposes of use and modify the surface of the mineral fiber product. Such products are therefore unac¬ ceptable for uses not requiring such a coating or impreg¬ nating layer. In such a case, the user would reject a product nevertheless coated, not only for technological reasons, but also because of the considerably higher price related to the coating or impregnating layer. Uncoated mineral wool products, on the other hand, present an open surface structure through which e.g. un- fiberised material (beads) and dust from the product in¬ terior may pass to the outside, particularly if the prod- uct is, for instance, compressed during handling. Such release of loose matter may be found to be irritating, for example by hobby workers processing the material. In view thereof, it is an object of the present in- vention to create a mineral wool product having such an impregnating layer which does not modify the surface structure in an unacceptable manner compared with the un¬ coated or unimpregnated product and yet forms a barrier against trickling particles and dust, and can be realised in large-series production without excessively raising the cost of the product. This object is achieved in that the impregnating sub¬ stance adheres to the individual fibers of the mineral wool product within a region that is defined by the im¬ pregnating depth while enclosing them without sealing the gaps between the fibers, allowing the fibrous surface to retain an open surface structure. A mineral wool product attaining this object is ob¬ tainable by applying an impregnating mass containing a carrier fluid for the purpose of its application, by working the impregnating mass into the product surface and subsequently drying the impregnating mass in order to volatilise the carrier fluid if the impregnating mass is foamed prior to its application. Hereby it is achieved that the foam mass foamed to the five- or sixfold volume and having a very low appar- ent density easily penetrates into the surface of the mineral wool product and entirely encloses the fibers there without exerting any essential mechanical forces on them. The loose foam mass may gently be impressed into the surface to a depth which is essentially determined by the thickness of the impressed foam layer, e.g. with a doctor blade. Even providing an impregnating layer on a single major surface may be of interest as a barrier against trickling particles for several applications, such as overhead assembly. For the purpose of providing an impregnating layer on both major surfaces, the mineral wool product e.g. provided in the form of a felt may sub¬ sequently be turned over and impregnated on its opposite major surface in the same manner. If the front surfaces are to be impregnated, as well, it is best to provide them with impregnating mass by an immersion process in which the respective edge of the felt web to be impreg¬ nated is dipped into the foam. As a matter of course, all of these surfaces can be impregnated in this or another, however identical way. All of these processes can be man¬ aged well in terms of production technology, also in large-series production, and may thus reliably be imple¬ mented without incurring any excessive additional costs. During drying or curing, the applied foam degenerates in such a manner that the foam bubbles burst by and by, with the impregnating mass thus released from areas in between the individual fibers attaching to the fibers by adhesion and coating them. Depending on the consistency of the impregnating mass, bridges of impregnating mate¬ rial may still span gaps between neighboring fibers, how- ever in any case pore-like openings between the fibers are opened. Due to the considerable increase in volume, wetting and impregnating the surface of the mineral wool product can be realised by means of a very small amount of im¬ pregnating mass, resulting in considerable savings of raw material and overall production costs compared with con¬ ventional coating layers. In addition there is a reduc¬ tion of the drying time or of the required drying capaci¬ ties, further supporting low-cost production. Where the impregnating mass also introduces substances not desir¬ able under certain viewpoints, their amount is corre¬ spondingly reduced, thus resulting in a correspondingly reduced expense for neutralising possible undesirable ef¬ fects. When using organic substances in the impregnating mass, for example, while it is necessary to obtain a good fire protection classification endangered by these, such as e.g. material class A2 - fireproof construction mate¬ rials - as specified by DIN 4102, the fire load is re¬ duced due to reduction of the amount of the impregnating material and concurrent reduction of the amount of or¬ ganic substances. Consequently, the use of fireproofing agents may be minimised or restricted to non-pollutant ones, e.g. fireproofing agents releasing nitrogen or water. This impregnating layer, which consequently can also be introduced into large-series production at relatively low additional costs, in any case results in an open sur¬ face structure, however at a more or less strongly re- duced pore size of the openings. Such a reduction is brought about already due to the simple fact that the fi¬ bers are enclosed by the impregnating mass, but addition¬ ally also through the bridges of impregnating material remaining at individual locations between neighboring fi- bers located at a distance from each other after the car¬ rier fluid has dried. In conjunction with the quite con¬ siderable impregnating layer depth of at least several millimeters, an effect similar to that of a labyrinth seal results from the random fiber orientations: whereas air may penetrate through the impregnating layer without essentially being impeded, solid matter on its passage through the impregnating layer will meet a plurality of obstacles and in all probability be trapped before emerg¬ ing at the surfaces of the impregnating layer. In this manner, the impregnating layer forms an effective barrier against dust and trickling particles. Furthermore the impregnating layer also brings about a change in the consistency of the product surface, which may be usef l for many applications. Thus in any case there results a more or less distinct mechanical strengthening of the mineral wool surface, and thereby an increased resistance to wear and erosion. Even if such additional effects by themselves frequently would not be worthwhile the additional expense for producing a product according to the invention, it can be of interest to utilise them once the product is available. Where the coloration of the impregnating layer is adapted to the coloring of the mineral wool, the former is hardly conspicuous to the eye, particularly as it is for the overwhelming part arranged underneath the top fi¬ ber layers of the mineral wool product and therefore hid¬ den. Consequently the risk of lacking acceptance by indi¬ vidual first users is low. On the other hand, however, even with first users acceptancy may be increased and the positive value of recognition by experienced users may be improved through an agreeable color design of the impreg¬ nating layer itself. It is of quite particular importance that the impreg¬ nating material in any case encloses practically all of the fibers on the surface. These are therefore provided with a coating that may strongly modify the tactile be¬ havior in a desired manner if the impregnating material is aptly chosen. In analogy to the known case e.g. of plastic-coated metal, a tactile impression if necessary entirely different from mineral materials such as glass may be created, such as a softer and - due to a lower co¬ efficient of heat transfer to skin - warmer tactile sen¬ sation which altogether is judged to be more agreeable. As agreeable gripping properties are desired particularly with mineral wool products, this aspect gains a particu¬ lar importance also independently from the function of a barrier against dust and trickling particles. The foam of an impregnating mass containing a carrier fluid such as water may be produced through foaming by blowing gas as is known per se. Preferably, the foam ac¬ cording to the invention is, however, produced mechani¬ cally according to the mechanical frothing method or by means of dissolver disks. Herein a spreadable foam is formed by beating in air and may be applied to the prod¬ uct surface and gently worked into the product surface by pressure. The carrier fluid such as water, which volatil¬ ises later on, also has the purpose of lowering the vis- cosity of the impregnating mass to such a degree that me¬ chanical frothing by the mechanical frothing method by means of dissolver disks is facilitated. The mixture of substances preferably used for the im- pregnating mass to be applied is an aqueous mixture of a siliceous binding agent such as particularly silica sol (colloidal silicic acid), plastic dispersion, foaming agent and foam stabilising agent, which may contain a fireproofing agents and further additives if necessary. Due to the plastic dispersion, which may be added in a considerable amount, namely in the same range as the ba¬ sic component (siliceous binding agent), the brittleness of the dried or cured impregnating layer is clearly re¬ duced and an elastically resilient behavior of the layer is produced. It appears that herefor plastic particles penetrate in between the Si0 particles and enable their elastic relative mobility. Such elasticity of the layer is very important for agreeable gripping properties of the product and moreover prevents the impregnating layer from being damaged, e.g. in the area of the corners, while the product is handled. A variety of products may serve as the plastic dis¬ persion. Particularly preferred in the framework of the present invention is Bayceram ® of Bayer AG, a polyes- ter/polyurethane dispersion satisfying the described characteristics and conferring particularly good elastic¬ ity. Good results were also achieved with Vinnapas ® Dis¬ persion EP177 of Wacker-Chemie, a vinyl acetate and eth- ylene copolymer, and with Mowilith ® Dispersion DM132 of Hoechst AG, a thermoplastic synthetic resin, however re¬ stricted to applications not requiring good water resis¬ tance in the case of Mowilith ® as Mowilith ® adsorbs up to 20%(wt.) water. The relatively high proportion of plastic dispersion results in an increased fire load, which may pose a prob¬ lem with applications requiring classification into a good fire protection class such as material class A2 (fireproof) as specified by DIN 4102. In such a case, ad- dition of fireproofing agents is frequently recommend- able. In accordance with an embodiment of the foamed im¬ pregnating mass used in accordance with the invention, it contains: 10 to 30%(wt.) silica sol (40%(wt.) content of solid Si0 2 ) 15 to 30%(wt.) plastic dispersion 0.3 to 1.5%(wt.) foaming agent 0.05 to 1.5%(wt.) foam stabilising agent fireproofing agent as required balance water. The amount of applied coating or impregnating mass conventionally is approximately 300 g/m 2 (dry) for usual applications, e.g. as a plaster-bearing layer for insu¬ lating panels for structure fronts. According to the in¬ vention, this amount may be specified to be much lower. Thus the amount of impregnating mass applied according to the invention is in the range between 10 and 100 g/m 2 (dry) . As a general rule, an applied amount of 20 to 60 g/m 2 (dry), particularly from 30 to 50 g/m 2 (dry) is sufficient according to the present invention. For usual applications, applied amounts in the range of 30 g/m 2 or slightly more are typical for the present invention. The above numeric indications relate to the weight of dried impregnating material. Such a foamed impregnating mass is suited not only for production of thus equipped mineral wool products by manufacturers, but can also be used for subsequent coat¬ ing or impregnating of mineral wool products which in¬ itially were purchased without such an impregnating layer. Such subsequent impregnation can be useful for a variety of reasons, however the invention gains particu- lar importance in connection with reforming mineral wool surfaces e.g. threatened by erosion and delaminations. Here, too, a corresponding strengthening of the surface may be effected by working in and drying such a foamed impregnating mass, which in view of the properties of the foam allowing easy introduction even in situ does not create any difficulties. For instance, a mineral wool in¬ sulating layer behind rear-ventilated claddings of a structure front of an industrial building can in this manner be secured against delaminations and erosion by wind forces and refurbished even after a long service life. Example 16%(wt.) silica sol (40%(wt.) solid content Si0 2 ) 12%(wt.) BACO SF4 (aluminum hydroxide) as a fireproofing agent 12%(wt.) Luvogard (phosphoric acid ester) as a fireproofing agent 20%(wt.) Bayceram ® (polyester/polyurethane dispersion of Bayer AG, water content 50%) l%(wt.) W53 foaming agent of Zschimmer & Schwarz l%(wt.) PS1 foam stabilising agent of Zschim¬ mer & Schwarz balance water This impregnating mass was frothed, by means of an agitator, to the sixfold of the volume prior to frothing and applied on the surface of a mineral wool panel and introduced therein by means of a doctor blade. Afterwards a panel thus coated was shortly cured in a through-type furnace. The foam structure decomposes during curing. This brought about a fine distribution of the impregnat¬ ing mass in a layer region adjacent the surface of the mineral wool panel. The foamed impregnating mass was ap¬ plied in an amount of approx. 50 g/m 2 and penetrated into the panel surface at a layer depth of about five millime¬ ters and enclosed the fibres adjacent the surface within the penetrating depth. The open surface structure of the panel was preserved. As a fireproofing agent, a combination of phosphoric acid ester and aluminum hydroxide is used. Phosphoric acid ester is considerably more expensive than aluminum hydroxide, however at the same time it serves as a sof¬ tener for the impregnating material. It follows that where a reduced brittlenes and an improved elasticity of the impregnating layer is required, the proportion of phosphoric acid ester in the fireproofing agent may be increased; otherwise it is kept low to minimise costs. The dried impregnating mass of the finished panel was provided in an amount of approx. 30 g/m 2 and presented the following composition: 21.1%(wt.) silica (solid content Si0 2 ) 26.3%(wt.) BACO SF4 (aluminum hydroxide) 26.3%(wt.) Luvogard (phosphoric acid ester) 21.9%(wt.) Bayceram® 2.2%(wt.) W53 foaming agent 2.2%(wt.) PS1 foam stabilising agent Further details, features and advantages of the in- vention can be seen from the following description of an embodiment by reference to the drawing, wherein: Fig. 1 shows a schematic representation of the process of introducing the foamed impregnating mass into the surface of a mineral wool product, and Fig. 2 shows a pictorial representation of the coated surface of the mineral wool product obtained thereby. Fig. 1 shows a schematic representation of how a min¬ eral wool product 1 having the form of a mineral wool felt on a production conveyor 2 is moved, in the course of its production, in the direction of an arrow 3. By means of a frothing device not represented here, impreg- nating mass has been frothed and charged on an applica¬ tion device 5 in the form of a foam layer 4. The foam layer 4 on the surface 6 of the mineral wool product 1 is carried along by the mineral wool product 1 in the direc¬ tion of arrow 3 and brought into the work area of a doc- tor blade 7. Upstream of the doctor blade 7, the foam of the foam layer 4 penetrates only slightly into the sur¬ face 6 of the mineral wool product because the foam layer 4 has only a very slight weight. Only through the pres¬ sure of the doctor blade 7 the foam layer 4 is pressed into the surface 6 of the mineral wool product 1, with a certain uniform penetrating depth t resulting in accor¬ dance with the consistency of the foam layer 4 and the surface 6 of the mineral wool product 1, with this pene¬ trating depth - just like the thickness of the foam layer 4 - being shown exaggeratedly large in the representation according to Fig. 1 for the purpose of clarity. As the doctor blade 7 has to exert only little pressure on the foam layer 4 in order to impress it into the surface 6, and as the doctor blade 7 furthermore only lightly touches the surface 6, if at all, the structure of the surface 6 is practically not modified by impression of the foam layer 4. Downstream of the doctor blade 7, the foam layer 4 impressed into the surface 6 forms an impregnating layer designated as 8, with the largely intact foam completely enclosing and wetting the fibers in the region of the surface 6, and sealing the previous openings in the sur¬ face 6 between the fibers. In the course of drying or curing the impregnating layer 8, however, the foam bub- bles burst and the impregnating mass concentrates on the individual fibers, with remainders of the previous three- dimensional foam structure between the fibers. A consistency of the coated surface resulting exem- plarily can be seen in Fig. 2, representing a top view of the impregnating layer 8 after drying or curing. Clearly discernible are the mineral fibers 9 adjacent the surface which are enclosed by impregnating mass. At the surface in the region between the fibers, bridge formations 10 of impregnating material resembling spider webs are partly discernible, between which, however, in any case, pores 11 of quite considerable size remain, such that the open structure of the surface is preserved. The impregnating layer 8 well allows the passage of air, but in a sense presents a filter layer for solid matter carried along by it. In comparison with an un- coated embodiment of the surface region of the mineral wool product 1, the pores 11 are reduced in size and sur- rounded by the surface of the impregnating material, so that with respect to the relatively large penetrating depth of the impregnating mass and their staggered ar¬ rangement due to random fiber orientations, the pores may function in the manner of a labyrinth seal to trap parti- cles. The tactile impression of the surface 6 is then de¬ termined almost exclusively by the impregnating layer, because the skin of a person touching it does not get into contact with uncoated mineral fiber material. Particularly on the side or front surfaces of the mineral wool product 1, forming an impregnating layer by immersing the edge of the product into a foam layer may be more recommendable than introduction by doctor blade as represented in Fig. 1. Apart from the fact that greater layer depths t may be achieved by means of doctor blade introduction, the results of either method are not noticeably different, such that the representation in Fig. 2 is also representative of an impregnating layer applied by immersion.

Claims: Claims 1. Mineral wool product (1) comprising an impregnated layer (8) on at least one surface thereof, the im¬ pregnating substance of which is located substan¬ tially in the region within the mineral wool adjacent the product surface (6), characterised in that said impregnating substance adheres to the individual fi- bers (9) of said mineral wool product within a region that is defined by the impregnation depth (t), such as to enclose the fibers without sealing the gaps be¬ tween them, allowing the fibrous surface to retain an open surface structure. 2. Mineral wool product (1) obtainable by applying an impregnating mass containing a carrier fluid for the purpose of its application, by working said impreg¬ nating mass into the product surface (6) and subse- quently drying said impregnating mass in order to volatilise said carrier fluid, characterised in that said impregnating mass is foamed prior to its appli¬ cation. 3. Mineral wool product according to claim 1 or 2, char¬ acterised by comprising an impregnated layer (8) on all of its surfaces (6). 4. Mineral wool product according to any one of claims 1 to 3, characterised in that inorganic siliceous bind¬ ing agents, in particular silica (Si0 2 ), and a plas¬ tic material are contained in said impregnated layer (8). 5. Mineral wool product according to any one of claims 1 to 4, characterised in that said impregnated layer (8) comprises a fireproofing agent. 6. Method for producing a mineral wool product according to any one of claims 1 to 5, characterised in that said impregnating mass is applied as a layer (4) of foam onto the surface (6) of said mineral wool prod¬ uct (1) and concurrently or subsequently worked into the surface (6) of said mineral wool product (1) by pressure, followed by drying the impregnated layer (8). 7. Method for producing a mineral wool product according to any one of claims 1 to 5, characterised in that said impregnating mass is provided in the form of foam, said surface (6) to be impregnated of said min¬ eral wool product (1) is immersed into said foam, and subsequently said impregnated layer (8) is dried. 8. Method according to claim -6 and/or 7, characterised in that said impregnated layer (8) is cured in tem¬ perature. 9. Method according to any one of claims 6 to 8, charac¬ terised in that said foamed impregnating mass is pro¬ duced by means of a mechanical method, shortly before its use, from a mixture containing an inorganic sili¬ ceous binding agent, in particular silica sol, a plastic dispersion, a foaming agent, a foam stabi¬ liser, in a given case a fireproofing (flame-inhibit¬ ing) agent, and a carrier fluid, in particular water. 10. Method according to any one of claims 6 to 9, charac- terised in that said foamed impregnating mass is ap¬ plied in amounts of 10 to 100 g/m 2 , preferably 20 to 60 g/m 2 , and in a particularly preferred manner 30 to 50 g/m 2 , all these figures on the basis of the weight of the dried impregnating substance. 11. Foamed impregnating mass, in particular for use in the method according to any one of claims 6 to 10, characterised by a mixture of 10 - 30% by weight silica sol (40% by weight of solid Si0 content) 15 - 30% by weight plastic dispersion 0.3 - 1.5% by weight foaming agent 0.05 - 1.5% by weight foam stabiliser fireproofing (flame-inhibit ing) agent as required balance water. which is foamed in accordance with a mechanical method. 12. Use of the impregnating mass according to claim 11, for coating mineral wool products installed in sup¬ porting structures, in particular for refurbishing the surfaces of insulating layers behind rear-venti¬ lated cladding elements.

Inventors: KUMMERMEHR HANS, KUMMERMEHR, HANS
Applicants: KUMMERMEHR HANS, SAINT GOBAIN ISOVER, ISOVER SAINT-GOBAIN, KUMMERMEHR, HANS
Application year: 1994
Main classification: C04B41
IPC codes: A01G31, C04B28, C04B41, D06M11, E04D11